Why not just take the muffler off completely and see if you get a performance gain. A saito will run just fine with no muffler pressure assuming you reset your needles and put the tank where it should be. I doubt you will see much, but it would be a worthy experiment. Fastest way to more power out of a Saito is 30% heli fuel and the the best prop for your application. I would start with working on finding the best prop combo first.